Valley,
Two important notes:
1. All custom modificaitons done in source code will be erased if you update the plugin. Always keep track of what and where you are changing.
2. Enable DEV mode in ow_includes/config.php before doing any changes. This clears cache on the server so that you can see your changes right away. Don't forget to disable ( set to false) DEV mode once you are done making/checking your changes.
File to edit:
ow_plugins/contactus/views/controllers/contact_index.html
Code to edit:
...
{form name='contact_form'}
Here comes custom text before the whole form
<table class="ow_table_1 ow_form ow_automargin" style="width: 500px;">
<tr class="ow_alt1 ow_tr_first">
<td class="ow_label">{label name='to'}</td>
<td class="ow_value">{input name='to'}{error name='to'}</td>
</tr>
...
Result: